Difficulties in the measurement of ocular rigidity in the living human eye have limited our knowledge on this parameter. However, ocular biomechanics have been implicated in the pathogenesis of this disease. The aim of this study is to characterize the pressure volume relation and quantify ocular rigidity and outflow facility in glaucomatous and normal eyes. For this purpose, the investigators have recently developed a manometric method for the measurement of ocular rigidity and outflow facility.